Took my usual flight at the local AMA airfield which I have flown at many times without problem. This time, I launched and flew flawlessly for about 5 minutes and was only about 100' away when all of a sudden, the drone either lost signal or had the motors stop and it tumbled out of the sky and crashed. It was a basically a total loss with repair estimated at $740. Does anyone have any ideas about "interference" or firmware problems?